A widely employed system for silver halide color photographic materials uses a light-sensitive silver halide emulsion and a so-called dye-forming coupler capable of forming a dye upon reacting with an oxidized product of an aromatic primary amine developing agent (hereinafter simply referred to as "coupler"). In particular, a combination of a yellow coupler, a cyan coupler and a magenta coupler is usually employed in color photographic light-sensitive materials. Among these couplers, pyrazoloazole couplers have recently been developed as magenta couplers.
Differing from the conventional 5-pyrazolone magenta couplers, the pyrazoloazole couplers have favorable characteristics in that they do not show side absorption in the vicinity of 430 nm; their absorption in the longer wavelength side sharply decreases to zero; they form magenta dyes having high color purity; the dye images obtained are excellent in light-fastness; and the like.
However, if the pyrazoloazole magenta coupler is dispersed in a silver halide emulsion layer using a conventionally employed high-boiling organic solvent, the resulting light-sensitive material, when exposed and developed, produces an inferior dye image to that produced by the conventional 5-pyrazolone couplers in terms of sensitivity, gradation and maximum density. Thus, there arise serious problems in putting pyrazoloazole couplers to practical use.
A color development solution contains an aromatic primary amine as a color development agent, which is much more subject to air oxidation under higher pH condition, thereby resulting in reducing an amount thereof to lower the development activity.
To prohibit such a drawback, a so-called preservative such as sulfites (e.g., sodium sulfite, etc.), bisulfites (e.g., potassium bisulfite, etc.), hydroxylamine and triethanolamine are added. However, when the sulfites are used as a preservative, an amount of the sulfite per unit volume of the agent may be varied depending on a contact with an air or an amount of the photosensitive material to be treated.
Furthermore, it is known that the sulfites react with an oxidation product of the aromatic primary amine development agent, i.e., quinone di-imine, to form addition product of the sulfites, thereby impairing a development activity. That is to say, the quinone di-imine which is formed by subjecting oxidation to the development agent by AgX, is competitively reacted by a coupling reaction with a coupler and an addition reaction with a sulfites at the same time. In the case of a coupler having lower coupling activity, a color development is suffered from a concentration of the sulfites to vary the photographical characteristics.